The patent EP 0 784 551 B1 discloses a brake control system in particular for vehicles used in off-road conditions. The brake control system comprises an electronic control unit and a brake control system to control brakes associated with each wheel of the vehicle. A driver interface in the form of a switch is used to cause the control unit to enter a hill descent mode when the vehicle is also detected to be in gear. In this mode, the control unit controls the speed of the vehicle by braking to slow the vehicle when a detected vehicle speed is above a preset target speed.
When driving off road with the hill descent mode active, it might be necessary to stop on a downhill slope, and then move off again. When moving away again from standstill, the brake pedal is released and the vehicle accelerates under the force of gravity until it reaches a preset target speed. When this target speed is approached, the control unit applies the brakes to maintain the target speed. On a steep slope, the rate of acceleration can be quite high requiring a large braking effort to prevent the speed of the vehicle from continuing past the target value, resulting in an aggressive and intrusive deceleration. If the vehicle is in wet or muddy conditions, i.e. where the traction is poor, this aggressive intervention can cause the electronic control to perform an anti-lock braking function which will over-ride the hill descent control function to prevent the wheels from locking. Hence the vehicle may accelerate above the target speed and lose stability. The same problem can occur with a vehicle without hill descent mode, but with an anti-locking device, when the driver wants to reduce the speed of the vehicle after moving off from a standstill position on a downhill slope. It is desired to provide an improved brake control system which overcomes or minimizes the above problems.